Specimen Collection

Tubes containing gel (SST and PST) are NOT acceptable

Please state dose, dose interval and time of last dose on request form

0.5 mL Paediatric Plain Blood (Always Required)

Red top plain tubes are the only acceptable paediatric tubes.

4 mL Adult Plain Blood (Preferred)

4 mL Adult Heparin Blood

Please note only DARK GREEN tubes are acceptable, LIGHT GREEN tubes with gel (PST) is NOT acceptable.

Reference Intervals

POSACONAZOLE

Trough >0.7mg/L for prophylaxis

Trough >1.0mg/L for treatment

UOM 14%

Turnaround Time: Between 4 days and 1 week

Batches performed twice per week.

(Usually Tues/Fri) .

For urgent requests please contact the on-call Chemical Pathologist chemicalpathologist@adhb.govt.nz

Assay Method

Platform: HPLC with photodiode aray detection

Diagnostic Use and Interpretation

DIAGNOSTIC USE

Posaconazole is a triazole antifungal agent used to treat patients >=18 years with invasive aspergillosis refractory to or intolerant of amphotericin B, itraconazole, voriconazole; oesophageal candidiasis, candidaemia refractory to or intolerant of amphotericin B, fluconazole, itraconazole; fusariosis, zygomycosis, cryptococcosis, chromoblastomycosis, mycetoma refractory to or intolerant of other antifungals; coccidioidomycosis. Treatment of oropharyngeal candidiasis in immunocompromised adults. Prophylaxis of invasive fungal infection in high risk patients >=13 years, e.g. prolonged neutropenia, haemopoietic stem cell transplant recipients. It is a restricted medication and approval is required for use.

The pharmacokinetics of posaconazole oral suspension are linear following single and multiple dose administration of up to 800 mg. Oral absorption of the posaconazole suspension is increased when given with food. Posaconazole is highly protein bound (> 98.0 %), predominantly to serum albumin. Clearance is primarily by glucuronidation rather than oxidative clearance by polymorphic cytochromes.

Steady-state plasma concentrations attained at 7 to 10 days following multiple-dose administration.

References

Therapeutic drug monitoring (TDM) of antifungal agents: guidelines from British Society for Medical Mycology. J Microbial Chemotherapy 2014; 69: 1162-1176

Chau MM, Kong DCM, van Hak SJ et al. Consensus guidelines for optimisong antifungal drug delivery and monitoring to avoid toxicity and improve outcomes in patients with haematological malignancy, 2014. Int Med j 2014; 44: 1364-88

Contact Information

Dr Sally Roberts, Clinical Microbiologist: ext 22705 mobile: 021 674 140

Specimen Transport Instructions for Referring Laboratories

Instructions for Referral to Labplus
Specimen collection	Do NOT use gel tubes
Specimen	Adult: 4mL Red top plain/ Lith Hep with no gel Paed: 0.5mL Red top plain
Aliquot Instructions	Centrifuge and aliquot 1 mL (refrigerate)
Aliquot Transport to Labplus	Refrigerate and transport at 4 o C

Last updated at 10:04:14 25/07/2025